To use voice-to-text dictation on OneNote for Mac:

1. Access the OneNote page you'd like to dictate on.
2. Press and hold Fn before pressing the fn + Esc combination. Once the microphone appears, you can release fn to enable the dictation tool.
3. Once the microphone has been clicked, a small window should appear at the bottom of the screen, prompting you to speak.
4. Start speaking while your words appear as text in the document.